A new Earth history for undergraduates
Preston Cloud 1988 Journal of Geoscience Education v36 p208-214

Cloud (1988) suggests writing an introductory course (non-majors welcome) around the first three or four billion years of Earth history. These early eons are very exciting from an Earth system standpoint because the atmosphere, hydrosphere, geosphere, and biosphere went through almost all of their major changes before the Cambrian.